Privileged helper for xdg-app

[Alexander Larsson]

On fre, 2016-01-08 at 14:35 +0000, Emmanuele Bassi wrote:
> > > You need a transaction object on the bus, sure; but you don't
> > > need
> > > weird queues, since the object will be kept alive until the
> > > operation
> > > is either terminated or cancelled.
> > 
> > With my proposal above (downloads happen outside the daemon) I
> > don't
> > really think it makes sense to cancel operations at all. While they
> > are
> > not instant, they are at most the order of ten seconds.
> 
> Sure; in our case installation operations can take a bit longer (we
> still target spinning rust drives and we do a bunch of work to ensure
> that we can roll back on error, as well as calling local
> post-installation hooks).

In general ostree operations are atomic. I.e. a pull is just
constructing a lot of objects in the ostree repo. It will not be
"commited" until the final update of the refs file. At any place before
that it can be aborted (and a GC-style operation can clean up whatever
leftovers that you may have).

That said, I guess the "export files and run triggers" part of an xdg-
app deploy is not atomic. Although it is idempotent, so you should be
able to just run the op again.

-- 
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 Alexander Larsson                                            Red Hat, Inc 
       alexl at redhat.com            alexander.larsson at gmail.com 
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